How to Build the PlusDuo Kid's Chair/desk

Necessity, the mother of inspiration.
 
A full two weeks before black Friday, my wife starts asking her sisters if they have any ideas on Christmas presents for their kids, so we can have the gift list ready for buying.
 
This year, one of my sisters-in-law asked if I could possibly make a pair of identical kids chairs.

The reason for this was one of those “It will come back to hunt you” gifts I made two years ago.
For our niece’s birthday, I made her a small chair and desk.

Without knowledge or intention, I had sowed the seeds of sibling rivalry.

It was a great success, but it also generated a problem: her little brother fought her constantly for the chair.
So for that Christmas, my sister-in-law asked it I could make a chair and desk for him.
Since I built the first chair and desk “by ear” I didn’t have a set of plans to build a second set. So the next set turned out a bit different from the first.

In the end, what happens is that both kids always want the SAME chair, so that’s why my sister-in-law wanted an identical set for presents this year.

Roughly at the same time, our son migrated his homework work area from the dining room table to my wife’s home office. The space is small, so he ends up doing his work sitting on the floor and using a small portable bed table as a work surface.
He really dislikes working like that, but he wants to be close to mommy, so now he also needs a small table and chair.
 
With all this building to do, I thought that maybe a better idea was to build a chair/desk combo, something like a school desk.

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I'm entering the plusDuo in the Design Competition. If you like it, feel free to vote for me. The mac and the laser cutter would be put to great use for many a future Instructables :D

I went online to see what was out there, but I didn’t find anything that I really liked. One of the biggest drawbacks to a school desk was that once its user outgrew it, it really wasn’t useful for anything else.
 
That got me thinking of my sister and her childhood chair. She’s had it since she was 5 and it’s not a really nice chair, but it’s sturdy and she still uses it as a one-step stepladder or to sit on when she’s doing something really close to the floor.
 
Then I remembered that back in school I used to sit in my chair backwards a lot, using the backrest to support my arms when we did group activities that required us to place our chairs in a circle.
 
That’s what sparked the idea of designing a convertible chair, one that was a conventional chair  “in the normal position” and that could transform into second a shape that would use the backrest as a desk in the “convertible position”, so that once the kids outgrew it, they could still keep it around and use it like my sister.
 
Now, this took me a few days to figure out, so when my wife asked me how things were going, I made a rough model out of cardboard and showed it to her. Experience has taught me that it’s much easier to explain some of my ideas to her like that.
 
She liked the idea and told me to go ahead and build it. I said that while the model proved the concept, it was really ugly. She was not convinced that the extra time I would take to come up with a nicer design would be worth it (risking missing the Christmas deadline), but in the end I was able to convince her to let me take the time to improve the look of the chair.
 
I went back to Google and started looking at kid’s chairs, taking ideas in.

I really liked a very modern looking bent plywood chair (450usd ouch) and really considered building something similar. I had always wanted to make something out of bent plywood, and this looked like the perfect excuse.

But looking at some Instructables that showed the process, I had to admit that I didn't have the time to be able to pull off the project in time for Christmas. 

So, I had to put down some ground rules for the chair.

1. It had to be easy to build
2. It had to be fast to build
3. I did not have to buy/build any tool to make it
4. Cheap to make (I had to make 4 copies - for my niece, nephew, and my two kids)
5. It had to look "kid nice", but not childish, so that the kids would want to keep it for years.

So, bet plywood was out of the question, normal plywood was in.

I have a book titled 1000 chairs from Taschen that I re-looked at (can you tell that I like chairs?).

Then, with my head filled with many many chairs, I got some thin cardboard from a cookie box, and sketched freehand the profile of a chair. I gave it a slight Androck profile, but more modern in style and a lot more boxy. I was careful with the center of gravity in the desk mode (no tipping over please).

That’s how Model 2 was born. I showed it to my wife and she had to admit that it really did look a lot nicer than the first one.
 
I used Sketchup to draw the plans and made a 1/2-scale model.
 
And I didn’t like it. Viewed from the side, I had made the legs and the backrest all the same width, and while it looked nice, it kind of looked a bit  “grown up”.

Also, I had made the front wider than the back, and the scale model showed that it didn’t look so nice in a bigger chair, so I discarded that part of the design.

I took a pencil and started to draw on the model making the legs thinner, changing proportions. I drew a line that made the bottom of the legs bigger than the top, and that hit home. It looked a lot cuter but without being too cartoonish, so I cut the model to its new design.

Also, as you can see from the pics of the finished chair, when it's in desk mode, it looks a little like a very boxy dog!

Another feature of the chair is that the backrest locks-in between the movable and fixed drawer tops so that when using it as a chair the backrest won't move.

Now the final version of the chair was ready, all it needed was a name.

Why did I choose the plusDuo?

Because the seat is also a drawer, the backrest a table top, the chair's legs plus seat become a stool, the back brace becomes the desk support and also acts as a carrying handle.

Make your template.

Here you have two options:

1. Use the included Sketchup file and print a 1:1 leg/back rest profile
2. Use the PDF files, a ruler and protractor to draw it on cardboard.

This is actually the most important part of the design, since the rest of the parts you have to cut are all derived of this basic shape.

Now, before you actually cut it, you must decide between two ways to cut the profile (see pictures):

1. Cut it out of a single piece of 12mm plywood (lots of wasted material)
2. Cut it out in two parts, that will be glued and joined.

I chose the second one, so there's an extra step I took that will not be needed if you make it out of a single piece.

Now, cut all the parts. There are a lot of angles, so please look very carefully at the PDFs, read all this Instructable first, look at all the pictures, ask me all the questions you want, before you cut.

Note:

1. All the drawer parts are 28cm in length.
2. The backrest top and bottom, as well as the drawer top are 27.8cm in length (just a little smaller so they wont scratch the paint)
3. Route the backrest guide using a straight 2mm bit.

Build the legs and backrest

1. Glue the leg+seat part to the leg+backrest part.
2. Glue and nail the part labeled A in the picture

Since I wanted to give the glued union as much support as possible, I glued and nailed a 5mm plywood face to the "front" of the parts.

Look at the pictures to get a clearer idea.

CAUTION!!

Don't forget, that while these parts are cut exactly alike, DO NOT ASSEMBLE THEM THE SAME!

You have to glue part A in the interior of both pieces, so that you have a right and left side. Don't glue two rights or two lefts.

Assemble the seat drawer.

1. Take one of the chair sides and glue and nail the bottom of the drawer (pic 1)
2. Glue and nail the front part of the drawer (pic 3)
3. Glue and nail the back of the drawer (pic 4)
4. Glue and nail the fixed top of the drawer (pic 5)

Assemble the chair.

1. Take the other chair side.
2. This will assemble into the drawer, just be careful that everything is straight and aligned before gluing and nailing.
3. Glue and nail the backrest crossbeam/ desk stopper/ carrying handle.

You can see that the chair is already painted before this step.
What happened?

Well, I had originally intended to leave the leg thickness to 17 mm (the width of the plywood) but it looked out of balance and took away from the look of the chair, so I went back and added the "leg expander".

It really made a difference.

Make them out of 5mm plywood for the inner face, and use 12mm ply for the perimeter.

Again, remember that there are left and right parts (look at the pic)

Build the backrest/desk

1. Glue and nail both runners to the backrest (pics 6 and 7)
2. Glue and nail the bottom of the "box" (pic 9)
3. Glue and nail the back of the backrest  using 5mm plywood (pic 10)
4. Glue and nail the top of the backrest. It should be flush to the front of the backrest and sticking out from the back  (pic 11)

Assemble the backrest to the chair.

1. Drill a hole straight thru and a shallow bigger one (the big one will hide the nail's head) on both sides of the chair (pic 12).
2. Place the backrest and place the nails. I placed a small plastic washer between the backrest and the chair's side (pic 13)
3. Glue the head of the nail in place, then fill and sand so you can't see the nail.

Assemble the drawer top to the chair.

1. Drill a hole straight thru and a shallow bigger one (the big one will hide the nail's head) on both sides of the chair (pic 14).
2. Drill a hole in the drawer top.
3. Place the drawer top and place the nails. I placed a small plastic washer between the backrest and the chair's side.
4. Glue the head of the nail in place, then fill and sand so you can't see the nail.

Place the table lock.

Now, this part will vary depending on the hardware you get.  Take a look at pics 16, 17 and 18 to see how I attached the one I got to the desktop bottom and the desk support.

To finish I painted the chairs with some kid friendly water based paint.

Here are two pictures of my son doing his homework in his new chair/desk.

He loves it so much (as does his sister and cousins) that they are using it for everything, including snack time!